I have a problem with entity views using blaze persistence library. I want to retrieve a list of Suppliers, each one with a list of Products but I'm getting an exception while creating Entity views model.
I'm using Blaze base configuration shown here.
This is my model (I have removed some fields to be more clear):
@Entity(name = "suppliers")
public class Supplier extends BaseEntity {
@Column(nullable = false, length = 100)
private String businessName;
@OneToMany(mappedBy = "supplier")
private List<Product> products;
}
@Entity(name = "products")
public class Product extends BaseEntity {
@Column(nullable = false)
private String name;
@Column(nullable = false)
private Integer price;
@ManyToOne
private Supplier supplier;
}
@EntityView(Supplier.class)
public interface SupplierWithProductsView {
Integer getId();
String getBusinessName();
List<ProductView> getProducts();
}
@EntityView(Product.class)
public interface ProductView {
Integer getId();
String getName();
Integer getPrice();
}
The exception I get at startup is the following:
Caused by: java.lang.IllegalArgumentException: Illegal occurence of [products] in path chain resolver!
at com.blazebit.persistence.parser.PathTargetResolvingExpressionVisitor.invalid(PathTargetResolvingExpressionVisitor.java:562) ~[blaze-persistence-core-parser-1.6.6.jar:1.6.6]
at com.blazebit.persistence.parser.PathTargetResolvingExpressionVisitor.visit(PathTargetResolvingExpressionVisitor.java:468) ~[blaze-persistence-core-parser-1.6.6.jar:1.6.6]
at com.blazebit.persistence.parser.expression.EntityLiteral.accept(EntityLiteral.java:50) ~[blaze-persistence-core-parser-1.6.6.jar:1.6.6]
at com.blazebit.persistence.view.impl.metamodel.MetamodelUtils.isIndexedList(MetamodelUtils.java:125) ~[blaze-persistence-entity-view-impl-1.6.6.jar:1.6.6]
at com.blazebit.persistence.view.impl.metamodel.MetamodelUtils.isIndexedList(MetamodelUtils.java:120) ~[blaze-persistence-entity-view-impl-1.6.6.jar:1.6.6]
at com.blazebit.persistence.view.impl.metamodel.AttributeMapping.determineIndexed(AttributeMapping.java:333) ~[blaze-persistence-entity-view-impl-1.6.6.jar:1.6.6]
at com.blazebit.persistence.view.impl.metamodel.attribute.AbstractMethodListAttribute.<init>(AbstractMethodListAttribute.java:61) ~[blaze-persistence-entity-view-impl-1.6.6.jar:1.6.6]
at com.blazebit.persistence.view.impl.metamodel.attribute.MappingMethodListAttribute.<init>(MappingMethodListAttribute.java:35) ~[blaze-persistence-entity-view-impl-1.6.6.jar:1.6.6]
at com.blazebit.persistence.view.impl.metamodel.MethodAttributeMapping.getMethodAttribute(MethodAttributeMapping.java:757) ~[blaze-persistence-entity-view-impl-1.6.6.jar:1.6.6]
at com.blazebit.persistence.view.impl.metamodel.ManagedViewTypeImpl.<init>(ManagedViewTypeImpl.java:319) ~[blaze-persistence-entity-view-impl-1.6.6.jar:1.6.6]
at com.blazebit.persistence.view.impl.metamodel.FlatViewTypeImpl.<init>(FlatViewTypeImpl.java:41) ~[blaze-persistence-entity-view-impl-1.6.6.jar:1.6.6]
at com.blazebit.persistence.view.impl.metamodel.ViewMappingImpl.getManagedViewType(ViewMappingImpl.java:892) ~[blaze-persistence-entity-view-impl-1.6.6.jar:1.6.6]
at com.blazebit.persistence.view.impl.metamodel.MetamodelBuildingContextImpl.getManagedViewType(MetamodelBuildingContextImpl.java:234) ~[blaze-persistence-entity-view-impl-1.6.6.jar:1.6.6]
at com.blazebit.persistence.view.impl.metamodel.ViewMetamodelImpl.<init>(ViewMetamodelImpl.java:88) ~[blaze-persistence-entity-view-impl-1.6.6.jar:1.6.6]
at com.blazebit.persistence.view.impl.EntityViewManagerImpl.<init>(EntityViewManagerImpl.java:271) ~[blaze-persistence-entity-view-impl-1.6.6.jar:1.6.6]
... 60 common frames omitted
I tried to take some tests by debugging and investigating in the library code and I found that if I add @MappingIndex to the products list in the view, the exception thrown seems more clear. I haven't fully understood how the mapping index works but maybe it is correlated. The following is the new exception:
Caused by: java.lang.IllegalArgumentException: There are error(s) in entity views!
The resolved possible types [java.util.List] are not assignable to the given expression type 'java.util.Collection<my.package.Product>' of the mapping expression declared by the attribute products[my.package.SupplierWithProductsView.getProducts]!
at com.blazebit.persistence.view.impl.EntityViewManagerImpl.<init>(EntityViewManagerImpl.java:285) ~[blaze-persistence-entity-view-impl-1.6.6.jar:1.6.6]
at com.blazebit.persistence.view.impl.EntityViewConfigurationImpl.createEntityViewManager(EntityViewConfigurationImpl.java:206) ~[blaze-persistence-entity-view-impl-1.6.6.jar:1.6.6]
at my.package.configurations.BlazePersistenceConfig.createEntityViewManager(BlazePersistenceConfig.java:44) ~[main/:na]
... other lines omitted
Anyone has any idea how to solve my problem?
Thanks in advance!
I tested your sample app now and I saw this exception:
Caused by: java.lang.IllegalArgumentException: Illegal occurence of [products] in path chain resolver!
at com.blazebit.persistence.parser.PathTargetResolvingExpressionVisitor.invalid(PathTargetResolvingExpressionVisitor.java:562)
at com.blazebit.persistence.parser.PathTargetResolvingExpressionVisitor.visit(PathTargetResolvingExpressionVisitor.java:468)
at com.blazebit.persistence.parser.expression.EntityLiteral.accept(EntityLiteral.java:50)
at com.blazebit.persistence.view.impl.metamodel.MetamodelUtils.isIndexedList(MetamodelUtils.java:125)
at com.blazebit.persistence.view.impl.metamodel.MetamodelUtils.isIndexedList(MetamodelUtils.java:120)
at com.blazebit.persistence.view.impl.metamodel.AttributeMapping.determineIndexed(AttributeMapping.java:333)
at com.blazebit.persistence.view.impl.metamodel.attribute.AbstractMethodListAttribute.<init>(AbstractMethodListAttribute.java:61)
at com.blazebit.persistence.view.impl.metamodel.attribute.MappingMethodListAttribute.<init>(MappingMethodListAttribute.java:35)
at com.blazebit.persistence.view.impl.metamodel.MethodAttributeMapping.getMethodAttribute(MethodAttributeMapping.java:757)
at com.blazebit.persistence.view.impl.metamodel.ManagedViewTypeImpl.<init>(ManagedViewTypeImpl.java:319)
at com.blazebit.persistence.view.impl.metamodel.FlatViewTypeImpl.<init>(FlatViewTypeImpl.java:41)
at com.blazebit.persistence.view.impl.metamodel.ViewMappingImpl.getManagedViewType(ViewMappingImpl.java:892)
at com.blazebit.persistence.view.impl.metamodel.MetamodelBuildingContextImpl.getManagedViewType(MetamodelBuildingContextImpl.java:234)
at com.blazebit.persistence.view.impl.metamodel.ViewMetamodelImpl.<init>(ViewMetamodelImpl.java:88)
at com.blazebit.persistence.view.impl.EntityViewManagerImpl.<init>(EntityViewManagerImpl.java:271)
The error means that the expression products, which is created behind the scenes for SupplierWithProductsView#getProducts, is illegal. This is an unfortunate side effect of the association being named the same as the entity ProductEntity i.e. @Entity(name = "products"). I created the following bug report for this and will look into this as soon as possible: https://github.com/Blazebit/blaze-persistence/issues/1450
In the meantime, you could rename the association to e.g. productList, seelingProducts or something like that. Alternatively, you could also rename the entity by using @Entity(name = "product") i.e. omitting the s.